The present invention relates to a control apparatus for a hybrid vehicle comprising an engine and a motor, or in particular to a hybrid vehicle control apparatus intended to improve the residual exhaust gas condition when the vehicle is in idle stop.
A hybrid vehicle which uses both an engine and a motor doubling as a generator (motor/generator) as motive power is considered an effective means to cope with both the energy problem and the environmental problem. Specifically, in a hybrid vehicle having an engine and a motor/generator, the motor is rendered to function as a generator to regenerate energy when the engine works negatively at the time of deceleration, for example. As compared with the vehicle having only an engine as motive power, therefore, the fuel efficiency is improved. Also, when the vehicle is stationary, the idling of the engine is prohibited. Further, when the engine is restarted, the revolution speed is increased by the motor to a rpm at which the engine can work independently, after which the engine is supplied with fuel to start fuel combustion. As a result, the unnecessary fuel consumption at the time of idling can be suppressed on the one hand, and the exhaust gas can be reduced at the time of starting on the other hand. In the hybrid vehicle, as described above, the engine and motor are controlled in collaboration with each other, and therefore both the fuel consumption and the exhaust gas can be improved as compared with the vehicle having only an engine.
At the time of what is called the idle stop when the engine stops as vehicle stops, on the other hand, the problem is posed of a deteriorated exhaust gas unique to the hybrid vehicle. Specifically, at the time of idle stop, the engine is stopped abruptly, and therefore the exhaust gas component remaining especially in the catalyst is adsorbed to the precious metal in the catalyst and may temporarily deteriorate the purification performance of the catalyst. When the vehicle is restarted, therefore, the problem is encountered that the residual gas is released out of the vehicle without sufficiently purifying the gas in the catalyst.
In order to obviate this problem, JP-A-10-288063 provides a technique for an apparatus which executes the operation with motor at the time of idling, while the idling of the engine is carried out when the catalyst temperature decreases below the activation temperature. On the other hand, JP-A-2000-97063 provides a technique for an apparatus in which the catalyst temperature, if lower than the activation temperature at the time of idle stop, is increased to the activation temperature.
The problem of the deteriorated exhaust gas unique to the hybrid vehicle which occurs at the time of idle stop is caused, as described above, by the fact that the abrupt engine stop leaves the exhaust gas in the engine intake pipe, the cylinders, the exhaust pipe and the catalyst, and these residual gases are released out of the vehicle without being sufficiently purified by the catalyst when the engine is restarted. Some action is required to prevent this situation.
The present inventor has acquired a new knowledge that a means for purifying the residual gas is required in the process between the intake pipe and the catalyst for obviating the aforementioned problem of the residual gas deterioration caused by idle stop. The conventional technique described above, however, is intended to prevent the catalyst temperature from decreasing below the active temperature by engine stop and includes no means for purifying the residual gas.
The present invention has been achieved in view of the problem described above, and the object thereof is to provide a hybrid vehicle control apparatus which can improve the exhaust gas deterioration unique to the hybrid vehicle in idle stop by purifying the exhaust gas remaining in the engine intake pipe, the cylinders, exhaust pipe and the catalyst.
In order to achieve the object described above, according to one aspect of the present invention, there is provided a control apparatus for a hybrid vehicle supplied with motive power by an engine operated by fuel combustion on the one hand and an electric motor/generator operated by electric energy on the other, the control apparatus comprising residual exhaust gas purification means for purifying the gas remaining in the intake pipe, cylinders, exhaust pipe and the catalyst of the engine.
In the hybrid vehicle control apparatus according to this invention having the configuration described above, as shown in FIG. 1, the gas remaining in the portions on the way from the intake pipe to the catalyst is purified by the residual exhaust purification means, and therefore the residual exhaust gas condition at the time of idle stop can be improved.
According to another aspect of the invention, there is provided a hybrid vehicle control apparatus specifically comprising, as shown in FIG. 2, accelerator pedal angle determining means for determining whether the accelerator pedal angle is not more than a predetermined value or not, wherein the residual exhaust gas purification means purifies the residual gas based on the output signal of the accelerator pedal angle determining means.
According to still another aspect of the invention, there is provided a hybrid vehicle control apparatus specifically comprising, as shown in FIG. 3, engine revolution means, which outputs, in the case where the fuel injection to the engine stops, a signal for rotating the engine by a force other than the explosion by combustion, based on the output signal from the residual exhaust gas purification means.
According to yet another aspect of the invention, there is provided a hybrid vehicle control apparatus,
wherein the engine revolution means rotates the engine by the turning effort of the electric motor/generator as shown in FIG. 4,
wherein the engine revolution means rotates the engine by the energy required for deceleration of the axle of the vehicle as shown in FIG. 5,
wherein the engine, the electric motor/generator, the transmission and the axle are connected in that order, and a clutch is interposed between the engine and the electric motor/generator, and the engine revolution means being adapted to rotate the engine through the axle by engaging the clutch for a predetermined time length in the case where the required drive force of the vehicle is not more than zero and the vehicle is decelerating, as shown in FIG. 6,
wherein the engine, the electric motor/generator, the transmission and the axle are connected in that order, and a clutch is interposed at least between the electric motor/generator and the transmission, the engine revolution means being adapted to disengage the clutch and rotate the engine by the electric motor/generator when the vehicle is stationary, as shown in FIG. 7, or
wherein the electric motor/generator, the engine, the transmission and the axle are connected in that order, and a clutch is interposed between the engine and the transmission, the engine revolution means being adapted to disengage the clutch and rotate the engine by the electric motor/generator when the vehicle is stationary, as shown in FIG. 8.
According to a further aspect of the invention, there is provided a hybrid vehicle control apparatus comprising:
control execution period calculation means for calculating the period of controlling the purification of the residual gas through the residual exhaust gas purification means based on the operating conditions of the engine or the electric motor/generator, the control execution period calculation means being adapted to calculate the control execution period based on the amount of air flowing into the engine;
wherein the engine includes catalyst upstream exhaust gas component detection means for detecting, directly or indirectly, the exhaust component upstream of the catalyst, the control execution period calculation means being adapted to calculate the control execution period based on the signal produced from the catalyst upstream exhaust gas component detection means;
wherein the engine includes catalyst downstream exhaust gas component detection means for detecting, directly or indirectly, the exhaust gas component downstream of the catalyst, the control execution period calculation means being adapted to calculate the control execution period based on the signal produced from the catalyst downstream exhaust gas component detection means;
wherein the engine includes a throttle valve for regulating the amount of air flowing into the engine, the throttle valve being adapted to open full during the period of controlling the purification of the residual gas through the residual exhaust gas purification means;
wherein the engine includes an exhaust gas reflux amount regulation valve for regulating the amount of exhaust gas reflux of the engine, the exhaust gas reflux amount regulation valve being adapted to be closed up during the period of controlling the purification of the residual gas through the residual exhaust gas purification means; or
wherein the engine includes a throttle valve for regulating the amount of air flowing into the engine, and the opening degree of the throttle valve and the rotational speed of the electric motor/generator are controlled to maximize the purification efficiency of the catalyst during the period of controlling the exhaust gas purification through the residual exhaust gas purification means.
According to a still further aspect of the invention, there is provided a hybrid vehicle control apparatus comprising an engine having a throttle valve for regulating the amount of air flowing into the engine;
wherein the opening degree of the throttle valve is controlled to maximize the purification efficiency of the catalyst during the period of controlling the purification of the residual gas through the residual exhaust gas purification means;
wherein, the vehicle having a battery for the motor/generator, the rotational speed of the motor/generator is determined in accordance with the storage amount of the battery;
wherein, the vehicle having a battery for the motor/generator, the control operation for purifying the residual gas by the residual exhaust gas purification means is prohibited in the case where the storage amount of the battery is not higher than a predetermined value; or
wherein, the vehicle having a battery for the motor/generator, the idle stop is prohibited and the engine is caused to idle in the case where the battery storage amount is not higher than a predetermined value.